Perpetual power sources generally provide time invariant power which can be used to supply electrical power to electronic devices. Examples of perpetual power sources include electrical outlets (or wall sockets), batteries, and the like. Electronic devices typically include a power controller (e.g., a power regulator) that regulates power from a perpetual power source to the electronic devices. FIG. 1 illustrates a conventional electronic system 100 including electronic devices 102, 104 that are powered by perpetual power sources. In particular, the electronic device 102 is powered from an electrical outlet 106 and receives regulated power through a power regulator 108, and the electronic device 104 is powered from a rechargeable battery 110 and receives regulated power through a power regulator 112. The electrical outlet 106 further provides power to a battery charger 114 to charge the rechargeable battery 110. The power regulator 108 and the battery charger 114 can receive electrical power from the electrical outlet 106 through an AC to DC converter 118.
In general, conventional power controllers—e.g., power regulator 108, 112, and battery charger 114—are designed only to operate based on a perpetual power source. Note: batteries (rechargeable and non-chargeable) are considered to be perpetual sources as batteries substantially maintain a constant voltage output until depletion. For example, FIG. 1B shows a graph 116 that depicts the power amplitude of an output of the electrical outlet 106 and the rechargeable battery 108. As shown in the graph 116, the power amplitude of the output of both the electrical outlet 106 and the rechargeable battery 110 are substantially constant over time. Conventional power controllers cannot generally operate if a perpetual power source is not present within an electronic system.